1. Field of the Invention
This invention pertains to an ashless mineral lubricating oil composition which has been modified to enhance its rust inhibiting properties by the addition thereto of a hydrocarbyl substituted polyhydric ester.
2. Description of the Prior Art
The art to which this invention relates is already aware, inter alia, of the following U.S. Pat. Nos. 1,888,023; 2,353,830; 3,458,444 and 3,794,586.
U.S. Pat. No. 1,888,023 discloses a color-stabilized lubricating oil composition containing a primary, secondary or tertiary aliphatic amine or hydroxyalkylamine.
U.S. Pat. No. 2,353,830 discloses a lubricant for an air pump containing tri-ethanolamine stearate and comprising 80 percent of water.
U.S. Pat. No. 3,458,444 discloses a rust inhibited mineral lubricating oil composition containing the reaction product of an alkenylsuccinic acid or anhydride and an N-hydrocarbyl diethanolamine.
U.S. Pat. No. 3,794,586 describes a lubricating oil composition containing a hydroxyalkyl-substituted polyamine.